Assemblies of tool bits and collets are well known in the prior art. That art also is aware of having the tool bit activate the collet for opening the collet to receive the tool bit and then axially restrain the tool bit in the collet. Those arrangements commonly employ a collet having a ball and a tool bit having a groove which receives the ball for providing axial restraint of the tool bit in the collet. Also, there is a spring-urged collar which forces the ball into the groove.
That prior art of course requires that there be a ball, and that the ball be under the control of the collet and the collar. In that arrangement, there must not only be a ball, but the collet must be arranged to hold the ball for placement into the groove. That ball, collet, and groove assembly requires those special parts and special assembly process steps to achieve the assembly where the ball is employed.
The present invention improves upon the prior art by having a tool bit that activates a collet to open the collet and thereby receive the tool bit and to then have the collet close onto the tool bit, and the tool bit is then restrained both rotationally and axially relative to the collet, all without a ball and with fixed surfaces axially restraining the tool bit. To achieve this improvement, the tool bit and collet have camming surfaces which are interengaged upon insertion of the tool bit into the collet for expanding the collet into the tool bit receptive mode. Of course, that is accomplished without the need for those specially dimensioned and hardened balls, and without the need for controlling the balls, such as when assembling the parts together.
Additionally, the present invention provides for automatic retraction of the collet-holding collar, and that is achieved simply upon, and at the time of, insertion of the tool bit into the collet. There can be fixed surfaces on the tool bit and the collet and the collar, rather than loose and movable balls, all of which act as camming surfaces to perform the functions mentioned above.
Still further, in the axial restraint of the tool bit in the collet, there is no need to utilize or rely upon movable balls for that restraint, Instead, there are fixed surfaces on the tool bit and the collet for that function, and thus the restraint is more accurate and reliable compared to the prior art tool bit holders.
A method for arranging the tool bit and collet in an assembled relationship is also included in this invention. Opening the collet, and the release of the collet holding collar, and the closing of the collar onto the collet are all achieved by surfaces respectively fixed on those moving parts, and moving against each other, in response to the one action of the insertion of the tool bit into the collet.